int getHeightSubTree(Node* node)
    {
        if (node == nullptr)
        {
            return 0;
        }
        int left, right;
        if (node->left_ != nullptr)
        {
            left = getHeightSubTree(node->left_);
        }
        else
        {
            left = -1;
        }
        if (node->right_ != nullptr)
        {
            right = getHeightSubTree(node->right_);
        }
        else
        {
            right = -1;
        }
        int max = left > right ? left : right;
        return max + 1;
    }